Email Bounce Rate
Email MarketingAlso: Bounce Rate · Hard Bounce · Soft Bounce
Quick definition
Email bounce rate is the percentage of emails that failed to reach the recipient's inbox. Hard bounces are permanent failures, typically invalid email addresses. Soft bounces are temporary failures, such as a full inbox or a server that was temporarily unavailable. A high bounce rate damages sender reputation and reduces deliverability across your entire list.
How it varies across Australia
Industry standards for acceptable bounce rates: hard bounces below 0.5% per send and total bounce rate (hard plus soft) below 2%. Australian email marketers using permission-based lists with regular hygiene should maintain hard bounce rates well below 0.3%. Higher rates indicate list quality issues that need addressing.
See retention benchmarks →Permanent delivery failure. The email address doesn't exist, the domain doesn't exist or the recipient has permanently blocked messages from your server. Hard bounces should be removed from your list immediately.
Temporary delivery failure. The mailbox is full, the server is temporarily unavailable or the message is too large. Most platforms retry soft bounces automatically and convert them to hard bounces after several failed attempts.
Email providers assign a reputation score to your sending domain and IP address. High bounce rates damage this score and cause future emails to land in spam or be blocked entirely. Sender reputation is hard to rebuild once damaged.
What it actually means
When you send an email, the receiving mail server either accepts it or rejects it. A rejection is a bounce. The type of bounce tells you what happened and what to do next.
Hard bounces happen when the email address is invalid: it doesn't exist, the domain doesn't exist or delivery has been permanently refused. There is no path to delivery. Remove hard bounces immediately. Every subsequent attempt to send to a hard bounce address damages your sender reputation.
Soft bounces happen for temporary reasons: the recipient's mailbox is full, the mail server is temporarily down or your message exceeds a size limit. Most email platforms automatically retry soft bounces for a set period. If delivery still fails after several retries, the platform converts the soft bounce to a hard bounce and suppresses the address.
Sender reputation is the reason bounce management matters commercially. Internet service providers track how many of your emails bounce. A high bounce rate signals that you're emailing stale, purchased or poorly managed lists. ISPs respond by routing your emails to spam or blocking them entirely. A damaged sender reputation affects every email you send, not just the ones to bad addresses.
Hard bounces are not a nuisance. They are an existential threat to your deliverability.
How to calculate it
Bounce Rate = (Bounced Emails ÷ Emails Sent) × 100
Worked example. You send 10,000 emails. 45 are hard bounces. 80 are soft bounces. Hard bounce rate = 0.45%. Total bounce rate = 1.25%. Both are within acceptable ranges. If hard bounces were 60, hard bounce rate would be 0.6%, which exceeds the 0.5% threshold and warrants a list audit.
The Australian context
Australia's Spam Act 2003 requires verifiable consent for commercial emails. Lists built with proper consent and double opt-in have significantly lower bounce rates than lists sourced from directories, purchased databases or events where consent was ambiguous. Australian businesses using legally compliant list-building processes should naturally maintain good bounce metrics.
Where people get this wrong
Related terms
Common questions
What is a good email bounce rate?
Hard bounce rate should be below 0.5% per send. Total bounce rate (hard plus soft) should be below 2%. Anything above these thresholds warrants a list hygiene review. Permission-based lists built with double opt-in consistently achieve hard bounce rates under 0.3%.
What causes a high email bounce rate?
Most commonly: invalid or stale email addresses, purchased or scraped contact lists, infrequent list maintenance allowing addresses to age and expire, or using single opt-in that allows typos and fake emails through. Fix with regular suppression list management and double opt-in for new subscribers.
What is the difference between a hard bounce and a soft bounce?
A hard bounce is permanent delivery failure. The address doesn't exist or has blocked you. Remove immediately. A soft bounce is temporary: full inbox, server issue. Most platforms retry automatically. After several failed retries, a soft bounce is converted to a hard bounce and suppressed.
Keep exploring
About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
How we think →